1. What makes water so special?

2. Water
A water molecule (H2O), is made up of three atoms --- one oxygen and two hydrogen. H O 1

3. So…what makes water so special?

4. Water is Polar!!!! The oxygen end “acts” negative
The hydrogen end “acts” positive
Causes the water to be POLAR, like a magnet.

5. Hydrogen Bonds Exist Between Water Molecules
Formed between a highly Electronegative atom (like oxygen in another water) of a polar molecule and a hydrogen
Weak bond, but strong in great numbers (ask about Crocodile Dundee)

6. Interaction Between Water Molecules
Negative Oxygen end of one water molecule is attracted to the Positive Hydrogen end of another water molecule to form a HYDROGEN BOND

7. What are the Properties of Water?1

8. Properties of Water
Cohesion 1

9. Properties of Water
Cohesion
Adhesion 1

10. Properties of Water
Cohesion
Adhesion
High Specific Heat 1

11. Properties of Water Cohesion Adhesion High Specific Heat
High Heat of Vaporization 1

12. Properties of Water Cohesion Adhesion High Specific Heat
High Heat of Vaporization
Less Dense as a Solid 1

13. Cohesion
Attraction between particles of the same substance ( why water is attracted to itself)
Results in surface tension (a measure of the strength of water’s surface) 1

14. Helps insects walk across water, but how is it helpful to people?
Cohesion …
Helps insects walk across water, but how is it helpful to people?

15. Adhesion Attraction between two different substances.
Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton.
Capillary action-water molecules will “tow” each other along when in a thin glass tube. 1

16. Adhesion Causes Capillary Action
Which gives water the ability to “climb” structures

17. High Specific Heat
Amount of heat needed to raise or lower 1g of a substance 1° C.
Water resists temperature change, both for heating and cooling.
Would you rather walk on sand or in water on a beach on a hot summer day?
Which would be warmer that night? Why? 1

18. High Heat of Vaporization1

19. Heat radiated from the sun warmed surface of the earth is
Water vapor forms a kind of global ‘‘blanket” which helps to keep the Earth warm.
Heat radiated from the sun warmed surface of the earth is
absorbed and held
by the vapor. 1

20. Water is Less Dense as a Solid
Which is ice and which is water? 1

21. Solutions & Suspensions
Water is usually part of a mixture.
There are two types of mixtures:
Solutions: substance dissolves in liquid
Suspensions: substance suspends in liquid
Come up with examples

22. Water is the solvent, salt is the solute salt water is the solution
Solutions
Water is the solvent, salt is the solute 
salt water is the solution

23. Suspensions
Substances that don’t dissolve but separate into tiny pieces.

24. Acids, Bases and pH H2O  H+ + OH-
One water molecule is made of two ions, (H+) and a Hydroxide Ion (OH-)
Hydrogen Ion Hydroxide Ion
Acid Base
H2O  H+ + OH-

25. Acids and Bases Acid: A solution with lots of H+ ions
pH 0 up to 7 is acid (acidic)
Base: A solution with lots of OH- ions
pH above 7 – 14 is basic (alkaline)

26. The pH Scale…acids Indicates the percent of H+ ions Ranges from 0 – 14
pH of 7 is neutral
Each pH unit represents a factor of 10X change in concentration
pH 3 is 10 x 10 x 10 (1000x) stronger than a pH of 6

27. The pH Scale…bases

28. Buffers
Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH (neutralization).
Produced naturally by the body to maintain homeostasis
Weak Acid
Weak Base